Question

Explain the principle of a potentiometer.

Answer 1

Principle of Potentiometer:

1. The basic principle of the potentiometer is that the potential drop across any section of the wire will be directly proportional to the length of the wire, provided the wire is of a uniform cross-sectional area and a uniform current flows through the wire.
2. A potentiometer is an electrical measuring instrument that is used to measure an unknown voltage.
3. In a potentiometer, a known voltage is provided which is compared to get the value of the unknown voltage.
4. There are two null points present for both the known and unknown EMF's.
5. At the null point, no current flows through the circuit and they are resistance free.

Working formula of a potentiometer

Given below is the circuit diagram of a potentiometer, where $E_1$ and $E_2$ are the known and unknown EMFs, $A_1$ and $A_2$ are the null points, and $L_1$ and $L_2$ are the distance from their respective null points.

The working formula of a potentiometer is,

$\frac{E_1}{E_2}=\frac{L_1}{L_2}$

Where, $E_1$ and $E_2$ are the known and unknown EMFs, and

$L_1$ and $L_2$ are the distance from their respective null points.